This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A252981 #6 Jul 23 2025 13:49:51 %S A252981 10,85,851,8487,67537,432842,5672484,36112108,129234988,322183180, %T A252981 635379492,1074743076,1640984356,2334103332,3154100004,4100974372, %U A252981 5174726436,6375356196,7702863652,9157248804,10738511652,12446652196 %N A252981 Number of nX6 nonnegative integer arrays with upper left 0 and lower right its king-move distance away minus 2 and every value increasing by 0 or 1 with every step right, diagonally se or down. %C A252981 Column 6 of A252983 %H A252981 R. H. Hardin, <a href="/A252981/b252981.txt">Table of n, a(n) for n = 1..210</a> %F A252981 Empirical: a(n) = 63438848*n^2 - 1019729920*n + 4176308004 for n>10 %e A252981 Some solutions for n=4 %e A252981 ..0..1..1..1..1..2....0..1..1..1..2..2....0..1..2..2..2..2....0..0..1..1..1..1 %e A252981 ..0..1..1..1..2..2....0..1..1..2..2..2....1..1..2..2..2..3....1..1..1..2..2..2 %e A252981 ..0..1..1..1..2..3....1..1..1..2..2..2....1..1..2..2..2..3....1..2..2..2..2..3 %e A252981 ..1..1..2..2..2..3....1..1..1..2..2..3....1..2..2..2..2..3....2..2..2..3..3..3 %K A252981 nonn %O A252981 1,1 %A A252981 _R. H. Hardin_, Dec 25 2014